A friend of mine probably would be considered a seat-mate with an awkward comment. He was sitting next to a lady that was visibly afraid of flying and tried to make conversation with him.
...
HIM: You don't have to be afraid of flying. It's must safer than driving your car.
HER: Yes...
HIM: Just the other week a friend of mine was killed in his car.
HER: Oh my, what happened?
HIM: A plane dropped onto the car.
HER: <silence for the remainder of the flight>
HTB.
That's one of the funniest things I've ever read.